The effect of monocular deprivation on the synaptic contacts of the visual cortex

Fifková, E.

doi:10.1002/neu.480010304

Cited by 120 publications

(19 citation statements)

References 31 publications

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“…This is consistent with observations that degeneration of retinal projection fibers is not evident until 5 days after enucleation (Chalmers and McCulloch, 1991a) and that morphological changes in visual centers appear only 10 days after unilateral visual deprivation in the adult rat (Fifkova, 1969(Fifkova, , 1970.…”

Section: Discussionsupporting

confidence: 92%

In vivo Cerebral Incorporation of Radiolabeled Fatty Acids after Acute Unilateral Orbital Enucleation in Adult Hooded Long-Evans Rats

Wakabayashi

Freed

Bell

et al. 1994

J Cereb Blood Flow Metab

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We examined effects of acute unilateral enucleation on incorporation from blood of intravenously injected unsaturated [1-14C]arachidonic acid ([14C]AA) and [1-14C]docosahexaenoic acid ([14C]DHA), and of saturated [9,10-3H]palmitic acid ([3H]PA), into visual and nonvisual brain areas of awake adult Long-Evans hooded rats. Regional cerebral metabolic rate for glucose (rCMRglc) values also were assessed with 2-deoxy-d-[1-14C]glucose ([14C]DG). One day after unilateral enucleation, an awake rat was placed in a brightly lit visual stimulation box with black and white striped walls, and a radiolabeled fatty acid was infused for 5 min or [14C]DG was injected as a bolus. [14C]DG also was injected in a group of rats kept in the dark for 4 h. Fifteen minutes after starting an infusion of a radiolabeled fatty acid, or 45 min after injecting [14C]DG, the rat was killed and the brain was prepared for quantitative autoradiography. Incorporation coefficients k* of fatty acids, or rCMRglc values, were calculated in homologous brain regions contralateral and ipsilateral to enucleation. As compared with ipsilateral regions, rCMRglc was reduced significantly (by as much as - 39%) in contralateral visual areas, including the superior colliculus, lateral geniculate body, and layers I, IV, and V of the primary (striate) and secondary (association, extrastriate) visual cortices. Enucleation did not affect incorporation of [3H]PA into contralateral visual regions, but reduced incorporation of [14C]AA and of [14C]DHA by - 18.5 to - 2.1%. Percent reductions were correlated with percent reductions in rCMRglc in most but not all regions. No effects were noted at any of nine nonvisual structures that were examined. These results indicate that enucleation acutely reduces neuronal activity in contralateral visual areas of the awake rat and that the reductions are coupled to reduced incorporation of unsaturated fatty acids into sn-2 regions of phosphatidylcholine, phosphatidylinositol, and phosphatidylethanolamine. Reduced fatty acid incorporation likely reflects reduced activity of phospholipases A2 and/or phospholipase C.

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Section: Discussionsupporting

confidence: 92%

In vivo Cerebral Incorporation of Radiolabeled Fatty Acids after Acute Unilateral Orbital Enucleation in Adult Hooded Long-Evans Rats

Wakabayashi

Freed

Bell

et al. 1994

J Cereb Blood Flow Metab

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“…Larger dendritic fields indicate more synapses, and this has been confirmed by electron microscopic analysis of the number of synapses per neuron (11)(12)(13). Similar effects have been reported in very early development between normal lightreared animals and visually deprived ones (14)(15)(16)(17)(18)(19)(20)(21)(22). In addition, in adulthood, experiences such as maze learning and handedness-reversal training increase dendritic field size relative to the same brain region in nontrained animals or relative to homologous contralateral brain areas within the same animal subserving nontrained regions of the periphery (23)(24)(25).…”

supporting

confidence: 69%

Evidence for active synapse formation or altered postsynaptic metabolism in visual cortex of rats reared in complex environments.

Greenough¹,

Hwang²,

Gorman³

1985

Proc. Natl. Acad. Sci. U.S.A.

173

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Animals placed in complex environments develop greater numbers of visual cortex synapses per neuron than animals housed in standard cages. Increased numbers of synapses could theoretically arise from (i) active formation of new synapses, or (ii) selective stabilization of constitutively produced synapses. The postsynaptic location of polyribosomal aggregates appears to be an indicator of newly forming synapses. In developmental synaptogenesis and adult reactive (to injury) synaptogenesis, polyribosomes are more frequently found at spine synapses and are more likely to appear in the spine head and stem. In the visual cortex of rats from complex environments, there was a greater frequency of spine synapses associated with polyribosomes, relative to rats from individual or group cages. Furthermore, a greater percentage of these spines had polyribosomes in the head and stem region. This suggests that synapses in this region may be actively induced by neural activity arising from the complex environment experience.The complex, or "enriched," laboratory environment, while quite different from the feral norm, has provided considerable evidence regarding possible forms of neuronal plasticity. Rats placed at weaning or in adulthood in these environments develop a thicker heavier occipital cortex with larger neuronal nuclei, more glial cells, and greater RNA content and enzyme activity per neuron, relative to rats housed in simple cages (1). Occipital cortex neurons have larger dendritic fields (2-6), greater density of postsynaptic spines on dendrites (7), and larger synaptic contacts in some layers (8), and synapses show additional morphological differences (9, 10) in the rats from a complex environment. Larger dendritic fields indicate more synapses, and this has been confirmed by electron microscopic analysis of the number of synapses per neuron (11)(12)(13) (26,27), connections may be overproduced, such that only a subset, activated by or appropriate to experience, is preserved. In adults, overproduction might take the form of constitutive (i.e., continuous, without regulation) generation of potentially transient synapses, selective retention of which depends on their appropriateness to ongoing neural activity (26-29). Second, synapses might be actively induced by experience-related neural activity. In this case, synaptogenesis would be local and temporally discrete, rather than widespread and continuous, although again only a subset of synapses produced in response to an experience might survive to encode it (30).These two hypothetical mechanisms predict different immediate consequences of a to-be-encoded event on synaptogenesis. The overproduction or constitutive generation model implies that exposure to such an event should not affect the rate of synapse production, but only the rate of synapse survival, whereas the induction model predicts that synaptogenesis will increase over baseline levels in response to novel experiences. Recently, a possible morphological indicant of newly forming synapses, the pres...

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“…The observation of longer and fewer synapses in the auditory cortex of the deaf mice is in agreement with the changes observed by Fifkova (1970) in the visual cortex of monocularly deprived rats. Different observations have been made by other authors studying the visual cortex of dark reared rats.…”

Section: Discussionsupporting

confidence: 90%

“…In the cerebral cortex, structural changes have been described in the visual area of animals submitted to visual deprivation (Valverde, 1967;Cragg, 1967;Fifkova, 1970;Vrensen & de Groot, 1974) and differences in structure have been observed among rats reared in so-called enriched or impoverished environments, these differences being mostly marked in the occipital cortex (Rosenzweig et al, 1972;West & Greenough, 1972). Finer studies of synaptic morphology have shown that rats raised in an impoverished environment had fewer synapses with subsynaptic plate perforations (Greenough et ai., 1978) and fewer flat or concave presynaptic endings (Wesa et al, 1982) these being considered as probably more efficient than convex presynaptic endings which might be non-functional according to Dyson & Jones (1980).…”

Section: Animal Studiesmentioning

confidence: 99%

Consequences of Auditory Deprivation in Animals and Humans

Périer¹,

Alegría

Buyse³

et al. 1984

Acta Oto-Laryngologica

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An electron microscopic study of the cerebral cortex of mutant deaf mice (Deol's dn gene) has shown differences in synaptic organisation between these mice and normally hearing ones. In the auditory cortex of the deaf mice, there are fewer synapses and these are larger than in the normally hearing, whereas there is no difference between these two categories in the visual cortex. These results are the reverse of those observed by other authors in the occipital cortex of rats raised in an enriched or impoverished environment. In humans, the functional consequences of early hearing loss have been investigated on moderately to severely deaf (60-80 db mean loss) youngsters, who have been tested for their capacity of categorical perception, auditory discrimination, and production of significant contrasts between stop consonants. Categorical perception was absent in alt but one subject. Auditory discrimination was poor for both the voiced-voiceless contrast and the place of articulation contrast. In the production experiments, the subjects had greater difficulty in producing the voiced-voiceless than the place of articulation contrasts. The possible relevance of these animal and human studies to cochlear implantation is discussed. I. ANIMAL STUDIESAuditory deprivation in animals can be obtained either by destruction of the inner ear or by restriction of auditory input.Ear destruction has been done by Levi-Montalcini (1949) and Powell & Erulkar (1961). It results in transsynaptic atrophy of the brainstem and thalamic auditory nuclei, this atrophy consisting of a reduction in size of the neurons without actual neuronal destruction, a lesion which might be reversible if proper stimulation could be restored.Complete suppression of auditory input to the intact animal cannot be achieved, because of bone conduction perception of the animal's own inner noises, so that only the results of auditory restriction are available (Wolf, 1943;Gauron & Becker, 1959). New-born rats submitted to such a restriction for several weeks or months have no difficulty in learning frequency discrimination but are less proficient than controls for discrimination of temporal sequences (Tees, 1967), and their hearing thresholds measured by electric response audiometry are elevated (Batkin et al., 1970). Webster & Webster (1977-79) observed that both postnatal auditory deprivation and experimentally produced conductive hearing loss in mice result in incomplete maturation of most brainstem auditory neurons. There is a critical period, before 45 days of age, during which acoustic stimulation has a more pronounced effect on neuronal maturation than the same stimulation given between 45 and 90 days. The changes observed were only partially reversible in animals which were submitted to auditory deprivation until 45 days of age and then placed in a normal acoustic environment. Bock et al. (1982), studying Deol's strain of deafness (dn) mutant mice, have recorded evoked potentials of normal or higher than normal amplitude at the level of the inferior colli...

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The effect of monocular deprivation on the synaptic contacts of the visual cortex

Cited by 120 publications

References 31 publications

In vivo Cerebral Incorporation of Radiolabeled Fatty Acids after Acute Unilateral Orbital Enucleation in Adult Hooded Long-Evans Rats

In vivo Cerebral Incorporation of Radiolabeled Fatty Acids after Acute Unilateral Orbital Enucleation in Adult Hooded Long-Evans Rats

Evidence for active synapse formation or altered postsynaptic metabolism in visual cortex of rats reared in complex environments.

Consequences of Auditory Deprivation in Animals and Humans

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